The present invention relates to fibrous nonwoven articles for stuffing, packing and the like, and more particularly, to lightweight, resilient and bulky materials which are suitable for thermal insulation, and are made up of substantially continuous single fine filaments stabilized on themselves by one or more surface binders.
Down and feathers are well known to have good properties as stuffing for articles such as for example, eiderdowns, sleeping bags, pillows, jackets and the like. However, they are very expensive because of their short supply, and require great care in order to avoid damage by insects and microbes. They also have inherent drawbacks, e.g., necessities of quilting to avoid uneven distribution in stuffed articles and of using expensive, closely woven or specially finished fabrics to avoid their penetration through the casing fabrics.
Natural or synthetic discontinuous, crimped fibers have also been used as stuffing in the form of wadding or laps. These fibers, however, are inferior to down and feathers for use as thermal insulation, rendering the stuffed articles unfavorably heavy in order to assure comparable thermal insulation. They also have the undesirable tendencies, during the course of time and over long use, of protruding through the enveloping material, agglomerating and losing the original bulkiness or disassociating because of their irreversible movement secured by crimp or surface scale.
It has been found that the addition of a bonding resin to bond the staple fibers at their cross-over points in wadding or in a lap produces improved support bulk and prevents the fibers from migrating. Therefore, it is today's commercial practice to cross-lap the webs and to spread a resin on the surface of the layered structure. It has also been recognized that too many bondings cause a loss in softness of the web.
There has been proposed stuffing material consisting of a highly corrugated web of continuous filaments which are directed substantially in the same direction and in which the undulations are fixed with the aid of an appropriate resin. The typical method of preparation of such webs consists in passing a tow of continuous filaments between two rollers driven at different peripheral velocities, taking up the corrugated web thus formed, spraying a bonding agent on the undulating lap and, finally, curing the bonding agent thus deposited. The stuffing materials formed in this manner retain the original alignment of filaments despite efforts to bring about a bulky form by corrugation. Also, the anisotropy sometimes exhibits an undesirable performance when in use, e.g., contraction toward the direction rectangular to the alignment of the filaments or breakage along the alignment, resulting in insufficient thermal insulating ability.
Although many proposals have been made for the provision of a stuffing material to solve the above-mentioned defects of staple fibers or tow and to simulate the desirable properties of down, such as for example, thermal-insulating ability and softness, the ideal stuffing material, equal or superior to natural down in these desirable properties, was not discovered prior to applicants' invention as disclosed and claimed in the present application.
It is, therefore, a primary object of the present invention to provide a thermal-insulating bulky product characterized by its structural make-up of substantially continuous, single fine filaments which are stabilized in the product by a surface binder on the filaments.
Another object of the present invention is to provide a thermal-insulating bulky product which may be uniquely accumulated, made of substantially continuous filaments which are stabilized in the product by a surface binder on the filaments.
Still another object of the present invention is to provide a new bulky product of a synthetic polymer which simulates down in its touch, in its response to compression, and in its thermal-insulating ability.
A further object of the present invention is to provide a bulky material made of substantially continuous filaments of a synthetic polymer which satisfies the requirements for stuffing and quilting goods.
Other objectss and advantages of the present invention shall become more apparent from the following detailed description, illustrative and comparative examples, and table, together with the accompanying drawings which illustrate the preferred process of the present invention.